ApolloError: Cannot read property 'type' of undefined

[Freire71]

Hi @jneurock, I'm getting this error while trying to execute a query that does not include any "type" property. When I inspect the ApolloError object does not give any valuable information about the error location. I've got no errors while trying to seed this "Contacts" Entity, however, the MirageJS query does not work properly. Could it be some conflict of dependencies? I'm using:

"@miragejs/graphql": "^0.1.13",
"graphql": "^16.6.0",
"@apollo/client": "^3.7.4",

Apollo Client Error object

Query that throws this error

query clients($take: Int) {
    contacts(take: $take) {
        edges {
            id
            firstName
            lastName
            location
            photoUrl
        }
        pageInfo {
            totalCount
        }
    }
}

Server.ts queries - I'm not using automatic query handling, because of intermediary pagination types involved (edges and pageInfo). The console.log call inside the contacts query does not get triggered, I've only gotten the error. I'm assuming that this custom resolver is not working, however, the listings query works fine

        Query: {
          listings: () => ({
            edges: this.schema.all('Listing'),
            pageInfo: {
              currentPage: 0,
              itemCount: 200,
              hasNextPage: false,
              hasPreviousPage: false,
              perPage: 200,
              pageCount: 1,
            },
            contacts: () => {
              console.log('>>>>> Contact query');
              return {
                edges: this.schema.all('Contact'),
                pageInfo: {
                  totalCount: 100,
                },
              };
            },
          }),
        },

[jneurock]

There may be several issues. It’s a little hard to tell.

I suspect the problem with the 'type' of undefined issue has to do with missing type info in the data returned. Mirage GraphQL will take Mirage records returned from resolvers and decorate them with the necessary type info for GraphQL. If you implement a custom resolver, you either need to exclusively return Mirage records or decorate the data with the type info as needed, e.g., a __typename field. Note: I could be totally wrong here and not fully remembering how this works.

I suspect the reason the contacts resolver isn’t working is that it’s nested under listings meaning it will only be called when resolving contacts as a field of listings.

Btw, Mirage GraphQL handles Relay Pagination out-of-the-box; however, it won’t include the extra pageInfo fields like you have.